There has been known a cooling system constructed by connecting plural low-temperature showcases such as freezing/chilling showcases or the like to a refrigerating machine in parallel through refrigerant pipes. A plurality of low-temperature showcases as described above are installed in a store such as a supermarket or the like, and provided to display or sell foods while freezing or chilling the foods.
In general, the refrigerating machine is configured by mounting and packaging one or plural compressors and condenser fans and a microcomputer for controlling them within a housing. The microcomputer controls the compressors and the condenser fans on the basis of a predetermined operation sequence to construct a refrigeration cycle together with the low-temperature showcases, thereby cooling the low-temperature showcases.
Recently, from the viewpoint of dealing with environment problems and reducing the energy cost, much attention has been recently paid to countermeasures for reducing power consumption of cooling systems even in stores such as supermarkets, etc. Therefore, a low-temperature showcase is provided with a microcomputer, an inside temperature sensor and an electromagnetic valve for controlling flow-in of refrigerant, and the microcomputer controls the opening/closing of the electromagnetic valve so that the inside temperature is kept to an inside set temperature, thereby increasing the operation efficiency. Furthermore, even a refrigerating machine is provided with a low-pressure side pressure sensor for detecting the refrigerant pressure at the low-pressure side, and a microcomputer controls a compressor so that the pressure at the low-pressure side is kept to a predetermined set value, thereby enhancing energy saving performance (for example, see patent document 1).
Furthermore, there has been recently implemented a cooling system in which the refrigerating machine is controlled to prevent needless cooling with keeping the inside temperature of the low-temperature showcase to the inside set temperature by cooperating the low-temperature showcase and the refrigerating machine with each other, whereby both maintenance of the cooling performance of the low-temperature showcase and enhancement of the energy saving performance of the refrigerating machine are performed. According to this cooling system, a controller for controlling the operation of the refrigerating machine is provided, and a proper value is set to the refrigerant pressure at the low-pressure side of the refrigerating machine and output to the refrigerating machine, whereby the energy saving performance of the refrigerating machine with keeping the cooling performance of the low-temperature showcase (for example, see Patent Document 2).